This invention relates to a programmable tuning selector for sequential actuation of a tuner in a receiver.
Programmable channel selection refers to the ability to skip (or to appear to skip) undesired channels during sequential channel stepping of a television tuner. Upon viewer actuation of a scanning switch, the tuning system sequentially steps through each television channel to allow a viewer to stop the scanning sequence on a desired channel. The channels which are not utilized in a given reception area should be rapidly scanned, giving the appearance of skipping the channel, while the channels which carry programs in a given reception area should be scanned slowly, providing a hesitation or dwell time which allows the viewer to decide whether he wishes to stop the automatic scanning sequence and view a particular channel.
For example, in Konopka U.S. Pat. No. 3,746,886 issued July 17, 1973, and assigned to the same assignee as the present application, individual program switches can be closed to cause a two-speed oscillator to rapidly step through neon stages which represent undesired channels. While the Konopka programmable tuning scanner operates satisfactorily, it has the disadvantage of requiring separate programmable channel switches in addition to the channel tuning potentiometers which are required in each neon memory stage to generate the tuning voltage for the varactor tuner.
Other types of television tuning scanners which can dwell on preselected channels are well known. Evans U.S. Pat. No. 3,602,822 and Imazeki U.S. Pat. No. 3,794,925 both show channel scanning systems using counters stepped by an oscillator to select desired channels. However, all such systems require separate channel selection switches to disable undesired channel representing stages (or alternatively to enable desired channel representing stages) which are in addition to the channel tuning potentiometers.
Prior scanning systems have automatically stepped until reaching the next channel, or have automatically stepped until the viewer stopped the stepping sequence. The first type of system has the disadvantage of requiring the viewer to manually intervene in order to continue stepping should the viewer not desire to view the next channel. The second type of system has the disadvantage of continuing to step indefinitely through all channels when completion of a scanning sequence through all available channels typically indicates that the viewer does not wish to change from the channel originally being received.